There are a lot of reasons I disable ratings. I think one of the main reasons is that I'd rather people comment and tell me what they did or didn't like. I prefer to do that myself, so I had one of the admins disable my ability to rate other people's maps as well. If I really like someone's map, or some concept or idea that was well-executed in the map, I'll usually favorite it instead so that I can come back to it later if I want to.